<script setup>
import { ref } from 'vue';
// !无需注册
import Child from './Child.vue'

const count = ref(1)

const updateCount = (n) => {
  count.value += n
}
</script>
<template>
  <div>
    App
    <hr/>
    <!-- <Child :count="count" @updateCount="count += $event"/> -->
    <Child :count="count" @updateCount="updateCount"/>
  </div>
</template>


